Needed - luggage carrier recommendation for SRX

I have a 2005 SRX and am going on a trip with five people for 10 days.  With a third-row seat, and minimal room for luggage, I need to utilize the space on the roof.  I also have the large retractable sunroof, so I really need to keep the luggage directly off the roof.
 
Does anyone know of a roof carrier that will do the job?
 
Thanks.
 
Scottre

 you didnt state how large of a carrier you need .. I tend to like these designs.

waterproof, hardshell, off the paint, aerodynamic (fuel saver)  ..

this one is $50.
12 cu ft, 48" Long x 26" Wide x 16" High
Item number: 330248223842

there are others .. similar design ..